Schizophrenic Jonathan Schwartz was recommitted to the Department of Health and Mental Hygiene after psych results showed he is not well enough to stand trial in the 2011 slaying of Barbara Weiden Schwartz Fischler.

The deranged man used a kitchen knife to repeatedly stab Fischler, the daughter of late financial guru Norman Weiden, who headed a charity after him, after the two got into an argument inside their posh East 85th Street apartment, prosecutors said.

“He has a history of psychological illness,” said defense attorney Daniel Gotlin.

Schwartz was deemed mentally unfit two other times and sent back to psychiatric centers for months at a time. He will return to court once he’s mentally stable and can understand the murder charges against him, his lawyer said.

Schwartz’s younger brother, Kenneth, committed suicide last year after learning his mom’s second husband nearly wiped out her $5.8 million fortune on risky short sales.